1. Field of the Invention
This invention relates to the architecture of a switching node that handles the D Channel out-of-band signaling protocol of an Integrated Services Digital Network (ISDN).
Typically, the application of such a node can be found in systems requiring D Channel message processing. More specifically, the present invention finds it primary utility in the area of digital networks implementing ISDN.
2. Glossary
The following terms may be used freely in this document:
ASP Assignment Source point. That entity in the network at layer 2 which manages the TEI values. PA1 B Channel The bearer channel, logically different from the D Channel. The B Channel does not carry any signaling in-band for all processing on ISDN. PA1 Basic Rate Interface A defined user-network interface. Contains 2 B Channels and a D Channel, logically multiplexed together at Layer 1. PA1 CCITT International Telegraph and Telephone Consultive Committee. An international body which establishes communication standards. PA1 CES Connection Endpoint Suffix. The Layer 3 identifier, similar to the TEI at Layer 2. The CES and TEI have a one-to-one correspondence. PA1 CO Central Office. PA1 DCE Data Circuit Terminating Equipment. PA1 D Channel The signaling channel is ISDN. 16 Kbps in the basic rate interface and 64 Kbps in the primary rate interface. PA1 Demux Demultiplexer. PA1 DIP Dual Inline Package. PA1 DLCI The LAPD address. DLCI=SAPI+TEI. PA1 DSL Digital Subscriber Loop. The connection between the network node and the customer. PA1 DTE Data Terminal Equipment. PA1 IC Integrated Circuit. PA1 ISDN Integrated Service Digital Network. PA1 ISO International Standards Organization. An international body of technical experts which proposes and establishes technical standards. PA1 LAPB Link Access Protocol Balanced. PA1 LAPD Link Access Protocol on the D Channel of ISDN. PA1 LSB Least Significant Bit. PA1 MSB Most Significant Bit. PA1 Mux Multiplexer. PA1 Out-of-Band Signaling When a separate logical channel is used to transport the signaling information. PA1 OSI Open System Interconnection. PA1 Primary Rate Interface A defined user network interface containing 23 B Channels (or 30 B Channels) and a D Channel (64 Kbps) logically multiplexed together at Layer 1. PA1 2B+D Two Bearer (2B) channels for carrying User data plus one signaling (D) Channel used in basic rate ISDN. PA1 23B+D 23 Bearer (23B) Channels for carrying User data plus one signaling (D) Channel used in Primary Rate ISDN. PA1 S, T, U References Reference points defined in the ISDN user-network interface. PA1 Peer Communicating Entities at the same given layer. PA1 SAPI Service Access Point Identifier. A part of the LAPD address. Identifies the type of Layer 3 entity associated with the call. PA1 TEI Terminal Endpoint Identifier. A part of the LAPD address, identifying at Layer 2 the unique terminal that is associated with the call information.